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Abstract:

One embodiment may take the form of a system for reducing the appearance
of optical effects in a display. The system may include an enclosure with
a first surface and a second surface. Furthermore, the system may include
spacers that may be deposited on the bottom face of the first surface
and/or the top face of the second surface, where the first surface may be
a touch panel and/or cover lens and the second surface may be a display
module. The spacers may be deposited in one layer with an anti-reflection
coating. The thickness of the coating may be less than the diameter of
the spacers.

Claims:

1. A method for reducing the appearance of optical effects in a display,
comprising: providing a first surface and a second surface at least
partially within an enclosure, wherein the first surface and the second
surface are separated by a gap having a width; and in response to a
diminishment of the gap's width, maintaining a minimum distance, at the
spacer, between the first surface and the second surface.

2. The method of claim 1, further comprising depositing an
anti-reflection coating on at least one of the back of the first surface
and the front of the second surface.

3. The method of claim 1, wherein the first surface is a cover lens and
the second surface is a display module.

4. The method of claim 1, wherein the first surface is a touch panel.

5. The method of claim 2, wherein the anti-reflection coating is
deposited by spin-coating.

6. The method of claim 1, wherein the anti-reflection coating is made up
of hollow beads.

7. The method of claim 2, wherein the spacers and the anti-reflection
coating form a single layer.

8. The method of claim 7, wherein the spacers and the anti-reflection
coating have the same refractive index.

9. The method of claim 7, wherein at least the anti-reflection coating is
a fluorinated polymer.

10. The method of claim 1, wherein the spacers are deposited in a random
pattern on at least the front side of the second surface.

11. The method of claim 1, wherein the spacers form a grid pattern on at
least the front side of the second surface.

10. A system for modifying the appearance of a display, comprising: a
first surface and a second surface; an enclosure at least partially
surrounding the first surface and the second surface; and a plurality of
spacers located between the first surface and the second surface, wherein
the plurality of spacers prevent the first surface from physically
contacting the second surface at the location of each of the plurality of
spacers.

11. The system of claim 10, wherein the plurality of spacers are located
on at least one of the back of the first surface or the front of the
second surface.

Description:

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a divisional of U.S. patent application Ser.
No. 12/347,556, entitled "REDUCING OPTICAL EFFECTS IN A DISPLAY", filed
on Dec. 31, 2008, now U.S. Pat. No. ______, which is incorporated by
reference as if fully disclosed herein.

BACKGROUND

[0002] 1. Technical Field

[0003] The present invention generally relates to displays and, more
specifically, to maintaining the appearance of a display by reducing the
appearance of optical effects on a display.

[0004] 2. Background Discussion

[0005] Many computing devices use electronic displays to present
information to a user. Such displays may be, for example, liquid crystal
displays ("LCDs"), organic light emitting diode displays, cathode ray
tube displays ("CRTs") and so on. A number of computing devices may
include displays and/or screens with touch panel functionality where the
user may select options and interact with the computing device via the
display.

[0006] In particular, the user may physically touch the computing device
with a stylus, finger, or any other appropriate object to select an
option displayed on the computing device screen. For example, a user may
use a stylus to select a date on a calendar displayed on the screen and
then proceed to type on a keyboard that may be displayed on the screen.
As the user brings the stylus into contact with the screen, the cover
lens may curve and contact the display located underneath due to the
physical pressure exerted thereon by the stylus. To achieve a compact
design, the cover lens may be positioned close to the display surface.
The variation of cover lens position in production can also result in a
contact with the display. These arrangements and contacts may give rise
to optical effects that distort images on the screen.

[0007] Thus, a method of correcting optical effects that may occur on the
display is desirable. Accordingly, there is a need in the art for an
improved method of providing a touch panel/cover lens that may be used
with minimal optical distortion in the display.

SUMMARY

[0008] One embodiment of the present invention may take the form of a
method for reducing the appearance of optical effects in a display. A
first surface and a second surface may be at least partially surrounded
by an enclosure and may be separated by a gap having a width. Generally,
unless the enclosure is partially transparent, the enclosure may not
surround the first surface. A minimum distance may be maintained, at the
spacer, between the first surface and the second surface. That is, even
when the first surface is pressed towards or otherwise deforms towards
the second surface, the at least one spacer ensures the surfaces remain
separated by the minimum distance. An anti-reflection coating may be
deposited on the back of the first surface and/or the front of the second
surface. Additionally, the first surface may be a cover lens and the
second surface may be a display module.

[0009] Another embodiment of the present invention may take the form of a
system for modifying the appearance of a display. The display may include
a first surface and a second surface, an enclosure at least partially
surrounding the first surface and the second surface and a plurality of
spacers located between the first surface and the second surface, wherein
the plurality of spacers prevent the first surface from physically
contacting the second surface. The plurality of spacers may be located on
at least one of the back of the first surface or the front of the second
surface. Additionally, the display may include an anti-reflection coating
deposited on at least one of the first surface or second surfaces.
Furthermore, the anti-reflection coating and the plurality of spacers may
form a single layer and may have similar refractive indices.

[0010] Yet another embodiment of the present invention may take the form
of a system for preventing the appearance of optical effects in a
display. The display may include an enclosure at least partially
surrounding a first surface and a second surface, a coating on the bottom
face of the first surface and on the top face of the second surface, and
a plurality of spacers located between the first surface and the second
surface, wherein the spacers are deposited at least partially within the
coating. The coating and the plurality of spacers may be deposited as one
layer, may have similar refractive indices and the coating may be a
fluorinated polymer anti-reflection coating.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 depicts a general electronic device with a display.

[0012]FIG. 2 depicts a cross-sectional view of a general electronic
device with a display.

[0013] FIG. 3 depicts a cross-sectional view of the same general
electronic display with touch panel functionality.

[0014]FIG. 4 depicts a cross-sectional view of another electronic display
with coatings.

[0015]FIG. 5 depicts an embodiment of the present invention as a
cross-sectional view of an electronic display with spacers inserted
between the two surfaces.

[0016]FIG. 6 depicts another cross-sectional view of FIG. 3A with a
stylus in contact with the touch panel.

[0017]FIG. 7 depicts a sample method for depositing spacers with a hard
coating as one layer onto a surface in a display.

[0018]FIG. 8 depicts another sample method for depositing spacers with an
anti-reflection coating as one layer, onto a surface in a display.

[0019] FIG. 9 depicts a general representation of a display with an
anti-reflection coating.

[0020]FIG. 10 depicts an embodiment of a display that includes spacers
and an anti-reflection coating with different refractive indices.

[0021]FIG. 11 depicts another embodiment as a system with spacers and an
anti-reflection coating with similar refractive indices.

[0022] FIG. 12 is a flowchart depicting a sample method for reducing the
appearance of optical effects in a display.

DETAILED DESCRIPTION OF EMBODIMENTS

[0023] Generally, one embodiment of the present invention may take the
form of a method for reducing undesirable optical effects formed on or in
the electronic display. In this embodiment, the electronic display may
include two surfaces. One of the surfaces may be a display module and
another surface may be a touch panel. There may be an air gap between the
two surfaces. Continuing the description of this embodiment, spacers,
such as spherical beads, may be provided on the front side of the display
module and/or the back side of the touch panel. The spacers may prevent
the two surfaces from coming into physical contact with one another to
reduce distortion in the electronic display caused by optical effects and
the spacers may be composed of a transparent material to prevent further
optical distortion caused by the spacers themselves.

[0024] Another embodiment may take the form of a system for preventing
optical effects that may occur on an electronic display. As discussed
with respect to the previous embodiment, this embodiment may include a
similar electronic device. In this embodiment, the surfaces may be glossy
and/or transparent. Continuing the description of this embodiment, the
spacers may be made of various transparent materials including, but not
limited to, glass, plastic (such as fluorinated carbon, polycarbonates),
sapphire, quartz, silicon oxide, generally and so on. Additionally, the
spacers may be hollow beads, where the walls of the beads may be composed
of solid materials or the spacers may be a solid transparent bead. The
spacers may be randomly deposited onto either one or both of the surfaces
and/or may be deposited in a pattern, such as an aligned grid, a
spiraling pattern and so on. The spacers may be deposited in any number
of ways including air spraying, spin coating, photolithography, slit
coating, embossing and so on.

[0025] Yet another embodiment may take the form of a system for preventing
optical effects that may occur on an electronic device. As discussed with
respect to the previous embodiments, in this embodiment, the system may
be a similar electronic device with the following differences. Continuing
the description of this embodiment, the system may employ spacers in
conjunction with anti-reflection coatings. The spacers and the
anti-reflective coating may be combined in one or multiple layers on
either one or both of the surfaces and both the spacers and
anti-reflective may have the same refractive index. In this embodiment,
the thickness of the anti-reflection coatings may be less than the
diameter of the spacer.

[0026] It should be noted that embodiments of the present invention may be
used in a variety of optical systems and image processing systems. The
embodiment may include or work with a variety of display components,
monitors, screens, images, sensors, computing systems, portable computing
systems, handheld electronic devices and electrical devices generally.
Aspects of the present invention may be used with practically any
apparatus related to optical and electrical devices, display systems,
presentation systems or any apparatus that may contain any type of
display screen. Accordingly, embodiments of the present invention may be
employed in computing systems and devices used in visual presentations
and peripherals and so on.

[0027] Before explaining the disclosed embodiments in detail, it should be
understood that the invention is not limited in its application to the
details of the particular arrangements shown, because the invention is
capable of other embodiments. Also, the terminology used herein is for
the purpose of description and not of limitation.

[0028] FIG. 1 depicts a sample electronic device display having a display
100. FIG. 2 depicts a cross-sectional view of the general electronic
device display 100 of FIG. 1. The cross-sectional view of FIG. 2 is taken
along line AA of FIG. 1. Generally, a user may view the electronic
display 100 from the general direction as indicated by the arrow 150 in
FIG. 2. The electronic device 100 may include two surfaces such as a
display module 110 and a cover 120. In most cases, the cover may be
located in front of the display module to protect the display module. The
area 112 of FIG. 2 may provide functionality to the display module 110
and may include, for example, various electronic elements.

[0029] Additionally, the relationship between the various elements in
FIGS. 2-6 are shown in an illustrative manner and the various elements
may be arranged in alternative configurations. For example, the size,
thickness and relationship between the elements may vary, the size air
gap may be thinner relative to the thickness of the display module 110
and the cover 120, the display module 110 may extend outwardly to meet
the outside enclosure and so on. In another example, in FIG. 4, a space
is shown between the coating 140 and both of the display module 110 and
the cover 120 for illustrative purposes as the coating 140 may be
directly deposited on the display module 110 and the cover 120.

[0030] Some devices may incorporate touch panel functionality; thus, a
touch panel 120 may be used in place of the cover. However, a touch panel
may instead form part of the cover or be laminated to the cover. The
surface 120 may be referred to herein as a cover lens, cover or a touch
panel for explanatory purposes. Additionally, the discussion herein
embraces any device with a display and a cover lens that may or may not
include a touch panel. The touch panel 120 of FIGS. 2 and 3 may be
transparent and both the touch panel 120 and the display module 110 may
have glossy surfaces. The touch panel functionality will be discussed in
further detail below. The electronic device 100 may include an air gap
between the two surfaces. The thickness of the air gap may depend on the
form factor of the electronic device 100. For example, as the profile of
the electronic device becomes smaller and/or thinner, the distance
between the touch panel 120 and the display module 110 may decrease.
Accordingly, the air gap between the two surfaces may decrease as well.
As the size of the air gap decreases, the optical effects that may
distort the appearance of the images on the display typically appear.
Although the discussion herein describes the gap between the two surfaces
as an "air gap," it may be apparent to one skilled in the art that other
gases or a vacuum may fill the gap. The optical effects will be discussed
in further detail below.

[0031] FIG. 3 depicts a cross-sectional view of the same general
electronic device 100 as in FIG. 2, with a stylus 130 in contact with the
touch panel 120. The cross-sectional view of FIG. 3 is along line AA of
FIG. 1. In FIG. 3, the electronic device 100 may include a touch panel. A
user may interface with the electronic device 100 by bringing the stylus
130 into physical contact with the touch panel 120. In FIGS. 2 and 3, the
user may interact with and/or control the electronic device 100 via the
touch panel 120 which may serve at least the purpose of protecting the
display module 110 and conveying data via stylus interactions. Generally,
the touch panel may sense physical contact through various technologies
such as capacitive sensing, resistive sensing, pressure detection and so
on. Additionally, various objects may be used to contact the touch panel
120. For example, a user may employ a finger, a stylus, a general writing
utensil and so on to interact with the touch panel 120 of the electronic
device 100. The stylus 130 is used herein for explanatory purposes only.

[0032] In FIG. 3, the stylus 130 is in contact with the touch panel 120.
The stylus 130 may cause the touch panel 120 to curve and/or "deform" to
such an extent that it partially comes into contact with the display
module 110. Generally, a surface's arc or curve may be expressed as a
radius of curvature. As the touch panel 120 momentarily curves, the touch
panel radius of curvature may change and contribute to the occurrence of
the optical effects. The radius of curvature is discussed in further
detail below with respect to the optical effects.

[0033] In FIG. 3, the back surface of the touch panel 120 may come into
contact with the front surface of the display module 110. The stylus may
also cause the touch panel 120 and the display module 110 to come into
near contact without physically touching as well. When the two surfaces
come into contact or near contact, the display appearance may be
distributed by optical effects such as wetting artifacts and/or Newton's
rings.

[0034] Wetting effects may occur when two glossy surfaces come into
contact or near contact with one another. Wetting effects may be
undesirable because the two surfaces may adhere to each other and may be
difficult to separate from one another once the surfaces come into
contact. When the two surfaces are in contact, the Newton's ring effect
may become more visible and the images on the display may become
distorted or more difficult to view. The energy states of the surfaces
and the wetting effect will be discussed in further detail below.
Accordingly, in FIG. 3, when the stylus causes the touch panel 120 and
the display module 110 to come into contact or near contact, the two
surfaces may adhere. Coatings, as discussed herein with respect to FIG.
7, may be deposited onto the surfaces to reduce the wetting effect.

[0035] Similarly, Newton's rings may commonly occur between two surfaces
that are in contact or near contact with one another. More specifically,
Newton's rings may appear when a lens with small radius of curvature
rests against a relatively flat surface such as plate glass. When light
passes between the two surfaces, the light paths may refract and reflect
and interfere to produce Newton's rings. For example, light may be
refracted and reflected as it passes from air to the lens and from the
lens to air due to the change in the index of refraction of the
transmissive mediums. Light may be reflected while traveling from air
into the lens and thereby undergo a 180-degree phase change, thus
destructively interfering with the light reflected inside the lens
(curved surface). The interference pattern may appear as alternating
light and dark concentric rings.

[0036] The appearance of the previously described optical effects may be
reduced by employing an anti-glare ("AG") coating. AG coatings may
consist of a rough layer of beads and may be approximately 100 microns
thick in certain embodiments. As shown in FIG. 4 (the cross-sectional
view of FIG. 4 is along line AA of FIG. 1), the AG coating 140 may coat
the front surface of the display module 110 and the back surface of the
touch panel 120 in order to provide a texture or roughness to the
surfaces. Thus, the issues of wetting and Newton's rings may be reduced
as the roughness may prevent the two surfaces from sticking together.
Although the AG coating may reduce these optical effects, the roughness
may itself diffract light and may dull the appearance of the display.
Further an AG coating on the touch panel or the display module 110 may
yield a "washed-out" appearance in sunlight making it difficult to use
the electronic device outside, a decrease in display contrast ratio and
sharpness and/or an optical effect referred to as "sparkling." Generally,
sparkling occurs when the surface roughness and/or beads of the AG
coating interfere with the pixels. When this happens, shiny spots may
appear in the images on the display or the images on the display may
"sparkle." Pixel interference and sparkling will be discussed in more
detail below.

[0037] Another method currently employed to reduce the appearance of
wetting and Newton's Rings is to employ a laminate display. Generally,
laminate displays may be formed by depositing a transparent electrically
conductive layer on a surface. Although employing a laminate display may
reduce the wetting and Newton's Rings effects, the process may add
manufacturing difficulties and complexity, thus reducing the product
yield and making this option less desirable. Additionally, lamination may
provide the benefit of increased sensitivity of the touch panel, but may
also cause undesirable ripples in the displayed image when the stylus
comes into contact with the touch panel. Lamination may also cause other
issues regarding reliability, color shift, the ability to rework the
product and so on.

[0038] Additionally, anti-reflection coatings 140 may be used to reduce
Newton's Ring effects between the display module 110 and the touch panel
120. As depicted in FIG. 4, the anti-reflection coatings may be used on
both the back surface of the touch panel 120 and the front surface of the
display module 110. Because the coatings may reduce the reflective
properties of the two glossy surfaces and may reduce the tendency to
adhere to one another, the visibility of wetting and Newton's rings may
be reduced.

[0039]FIG. 5 depicts a cross-sectional view of yet another electronic
display 300. The cross-sectional view of FIG. 5 is along line AA of FIG.
1. Similar to FIGS. 2, 3 and 4, the electronic display 300 may include a
display module 110 and a cover lens 120. The electronic display 300 may
include touch panel functionality, and, in this case, the cover lens 120
may be a touch panel. As shown in FIG. 5, the display module 110 and the
touch panel 120 may be included within an enclosure. The enclosure may
surround the display module 110 and the touch panel 120.

[0040] In FIG. 5, the electronic display 300 includes spacers 350 inserted
between the two surfaces. The spacers may be deposited on the back
surface of the touch panel 120 (not shown) or on the front surface of the
display module 310 (shown in FIG. 5). The spacers may be various shapes
including spheres, ellipses, parabolic forms and so on, and may be made
of various materials such as glass, plastic, silicon dioxide or any other
relatively transparent material. Additionally, the spacers may reduce or
eliminate wetting and Newton's Rings effects when deposited between the
two surfaces by preventing the touch panel 320 and the display module 310
from coming into physical contact with one another. The spacers may also
provide a physical barrier to prevent the touch panel 320 and the display
module 310 from coming into sufficiently close contact with one another
to provide adverse optical effects. That is, the spacers may be
physically "sandwiched" between the touch panel 320 and the display
module 310 so that at least a minimum space between the two surfaces may
be maintained at all times. This minimum space is approximately equal to
the size of the spacers, as depicted in FIG. 6. The minimum distance will
be discussed in further detail below.

[0041] As shown in FIG. 6, a stylus 330 may be in contact with the touch
panel 320. The cross-sectional view of FIG. 6 is along line AA of FIG. 1.
Similar to FIG. 3, the stylus 330 may push the touch panel 320 towards
the display module 310. In FIG. 6, however, as the touch panel 320 curves
downward, it may physically encounter the spacers before touching the
display module 310. Thus, the spacers may function as a barrier between
the touch panel 320 and the display module 310, generally ensuring the
touch panel 320 and the display module 310 approximately maintain at
least a minimum distance between the two surfaces. By maintaining at
least this minimum distance, the air gap is large enough that the optical
effects, both wetting and Newton's rings, may no longer manifest due to
the lack of appropriate conditions.

[0042] As previously discussed, optical effects such as wetting and
Newton's Rings may occur when two surfaces are placed into contact or
near contact with one another. For example, an incident light ray may
undergo reflection and refraction when passing through the top curved
surface. Generally, refraction may occur when a light wave travels from a
medium with a first index of refraction into another medium with a second
index of refraction. At the boundary between the two media, the light
wave phase velocity may change, which, in turn, may cause a direction
change as well. For example, a light ray may refract or "bend" as it
enters and leaves glass because there is a change in the indices of
refraction of glass and air.

[0043] Additionally, the index of refraction is a measure for the
reduction of the speed of light in a specific medium. As some examples,
silicon dioxide has a refractive index of approximately 1.5 and air has a
refractive index of approximately 1.0. Accordingly, light may travel
through silicon dioxide at approximately 0.67 times the speed of light in
a vacuum (1/1.5=0.67)

[0044] In one embodiment, refracted light may reflect off of a bottom
surface, such as the display module 310 of FIG. 6, and the light may
undergo a 180 degree phase change. The refracted and reflected light rays
may then interfere with one another, both constructively and
destructively, thus producing the light and dark rings characteristic of
a Newton's ring pattern. The radius of each ring, rn, may be defined
as follows:

rn=R(N-1/2)λ

where R is the radius of curvature of the top surface, N is the ring
number (for example, N=1 for the smallest bright ring, N=2 for the next
largest ring, etc. . . . ), λ is the wavelength of light and
rn is the radius of the Nth bright ring. The radius of the rings are
also dependent on the thickness of the air gap t:

2t=(N-1/2)λ

rn=R(2t)

Thus, by adjusting the thickness of the air gap, the radius of the rings
may also be affected. For example, the air gap may be large enough that
the radius of a given ring exceeds the physical dimensions of the
display. In such a case, no Newton's ring may be visible.

[0045] Returning to the discussion of FIG. 6, the spacers may be various
sizes. In one embodiment, the spacer size may be smaller than one quarter
of the subpixel dimension of the display. Generally, pixels are picture
elements and may be arranged into a grid pattern to display an image. The
number of colors that may be presented by a pixel may depend on the
number of bits per pixel ("bpp"). For example, a one bpp image may uses
one bit per pixel, thus each pixel may be either on or off and a two bpp
image may have four colors, a three bpp image may have eight colors and
so on. Some displays may not be capable of displaying or sensing
different color channels at the same site. These displays may divide the
pixel grid into single-color regions with separately addressable elements
which may be referred to as "subpixels." In one example, an LCD may
divide each pixel horizontally into three subpixels. By sizing the
spacers smaller than one quarter of the subpixel dimension of the
display, the interference between the spacers and the pixels may be
avoided, thus reducing the sparkling effect on a display image.

[0046] The spacer size may also be chosen to avoid or reduce the
likelihood of the spacers causing cosmetic defects in the display. As the
size of the spacer decreases, a user may be less likely to perceive the
spacers on the bottom surface of the touch panel 320 or on the top
surface of the display module 310. In one embodiment, the bead size of
the spacer may be approximately equal to or less than ten micrometers.
More specifically, the bead size may be, in one example, six micrometers.

[0047] In one embodiment, the density of the spacers on the surface may be
low enough to avoid the previously discussed optical effects caused by
the AG coating such as diffraction and/or a dull appearance to the
display. Additionally, the density of the spacers may be high enough to
prevent the display module 310 and the touch panel 320 from coming into
physical contact with one another. In one embodiment, any number of
spacers between ten and ten thousand spacers per square millimeter may be
deposited on facing surfaces of either the display module 310, the touch
panel 320 or both.

[0048] The spacers may be deposited onto the surface in random locations
or may be aligned in patterns. When depositing the spacers randomly
across the surface, the density of spacers may be higher than when
aligning the spacers in a pattern across the surface to ensure that an
adequate number of spacers exists in any given area to prevent contact
between the display module 310 and the touch panel 320. Alternatively,
the spacers may be deposited in any type of pattern such as a square
grid, a spiral, concentric circles and so on.

[0049] Any number of methods may be used to deposit the spacers onto the
surface including, but not limited to, air spraying, spin coating,
photolithography, embossing and so on. The employed method may vary
depending on whether the spacers are to be randomly deposited or set in a
pattern across the surface. Additionally, different methods may be used
depending on the precision needed for depositing the spacers. For
example, photolithography may be used to deposit the spacers in a
pattern, while spin coating may be used to randomly deposit the spacers
across the surface.

[0050] In another embodiment and as depicted in FIG. 7, the combination of
spacers 750 and anti-reflection coatings 740 may be used to reduce
wetting and Newton's ring effects. FIG. 7 provides an illustration of a
portion of the layers that may be deposited on at least one of the
display module 110 or the cover 120, as the layers cover or at least
partially cover the surfaces of at least one of the display module or the
cover. Anti-reflection coatings may be applied to surfaces to reduce
reflections. The anti-reflection coatings may consist of transparent thin
film structures with alternating layers of contrasting refractive
indices. The thickness of the layers may be selected so that the
reflected and transmitted light may interfere constructively and
destructively. The anti-reflection coating may be a single-layer
interference coating, multi-layer coatings, an absorbent coating and so
on.

[0051] Generally, an anti-reflection coating may form the top surface of
all the coatings and thereby reduce surface reflections of the display
110. Accordingly, the spacers may not be deposited on top of the
anti-reflection coating as no additional coatings may be deposited on top
of the anti-reflection coating to secure the spacers on the surface.
However, the spacers may be secured by depositing the spacers in
conjunction with the hard coating or anti-reflection coating in one
layer. Depositing the spacers and the anti-reflection coating in one
layer is discussed in further detail below with respect to FIG. 8.

[0052] In one embodiment, and as illustrated in FIG. 7, the spacers may be
mixed into the hard coating when the coating is a raw liquid material.
The hard coating may be deposited onto the base layer as shown in step 2,
where the base layer may be any material such as glass, polyethylene
terephthalate films ("PET films"), triacetyl cellulose films ("TAC
films") and so on. After the hard coating is deposited, it may cure and,
as shown in FIG. 7, the spacers may partially protrude beyond the hard
coating surface. As shown in step 3, the anti-reflection coating may be
deposited after the hard coating has finished curing. In certain
embodiments when the anti-reflection coating is deposited, its thickness
permits a portion of the spacers to protrude into the air gap.
Additionally, because the spacers may be deposited with the hard coating,
the method of depositing the hard coating may be selected so that the
density of spacers is high enough to ensure the top surface (e.g., touch
panel) may physically contact the spacer before it comes into contact
with the bottom surface (e.g., display module).

[0053] In another embodiment, and as illustrated in FIG. 8, the spacers
850 may be mixed into the anti-reflection coating 840. In this
embodiment, the hard coating may be deposited onto the base layer as
shown in step 1. After the hard coating completes curing, the
anti-reflection coating may be deposited on top of the hard coating as
shown in step 3. Since the spacers are already mixed into the
anti-reflection coating they are likewise deposited. Continuing the
description of this embodiment, the anti-reflection coating may be
selected so that the thickness of the coating (when cured) is less than
the diameter of the spacer beads. Thus, the spacer beads may protrude
from the anti-reflection coating to prevent the touch panel from
physically contacting the display module.

[0054] Next, the discussion moves to the refractive index of the
anti-reflection coating and the spacer beads. FIG. 9 depicts a typical
example of a combination of a hard coating and an anti-reflection layer
940 on a base layer. FIG. 9 provides an illustration of a hard coating
920 deposited on top of a base layer 910. In FIG. 9, an anti-reflection
layer 940 may be deposited on top of the hard coating 920 and the
anti-reflection layer may be a single layer anti-reflection coating which
may have a refractive index between the index of refraction of the base
layer (where the base layer may be glass, a PET film, a TAC film and so
on) and air.

[0055] As shown in FIG. 9, the anti-reflection layer 940 may be composed
of beads. The desired refractive index (e.g., one between the refractive
indices of the base layer and air) may be achieved by making the
anti-reflection layer out of hollow beads 940a. In FIG. 9, the wall of
the hollow beads may be composed of a solid material while the interior
contains air, a vacuum, or some other low index material. The effective
index of refraction of the hollow bead may be somewhere between the index
of refraction of the wall and the index of refraction of air. In one
example, the wall of the hollow bead may be made of silicon dioxide
("SiO2"). Continuing this example, the index of refraction for SiO2 is
approximately 1.5 and the index of refraction of air is approximately
1.0. The relative volume of the SiO2, sidewall and interior air may be
controlled in each bead to vary the effective refractive index from 1.0
to 1.5. In one embodiment, the effective refractive index may be
approximately 1.33.

[0056]FIG. 10 illustrates an example of a base layer, a hard coating, an
anti-reflection layer with an effective refractive index of approximately
1.33 and spacers with a refractive index of approximately 1.5. As
previously discussed with respect to FIG. 9, the anti-reflection coating
1010 may be made up of hollow beads 1010a with an effective refractive
index of 1.33. However, as illustrated in FIG. 10 for explanatory
purposes, the spacers 1050 may not be hollow and may have an index of
refraction of 1.5. As shown in FIG. 10, the index mismatch due to the
spacers may cause scattering or a deviation of the light path from other
than a path of specular reflection.

[0057] In one embodiment, the spacers may be solid beads (not shown) with
a similar refractive index to the anti-reflection layer. For example, the
anti-reflection layer may have an index of refraction of approximately
1.33 and the spacers may also have an index of refraction of
approximately 1.33. Thus, scattering may be reduced or prevented because
there may be little to no index mismatch between the spacers and the
anti-reflection layer.

[0058] Alternatively, in another embodiment and as depicted in FIG. 11,
the spacers 1150 may be included in the anti-reflection layer 1130 and
may also have a refractive index of approximately 1.33. Similar to the
anti-reflection layer of FIG. 10, the anti-reflection layer of FIG. 11
may also be made up of hollow beads 1130a with an effective refractive
index of approximately 1.33. FIG. 11 is distinct from FIG. 10 because the
spacers may also be hollow beads with an effective refractive index of
approximately 1.33. Because the spacers have an index of refraction that
is substantially similar to that of the anti-reflection coating, there
may be no index mismatch, and thus, no scattering.

[0059] In yet another embodiment, the anti-reflection coating may be
composed of a single layer of polymers which may have a refractive index
between the refractive indices of glass and air. That is, the polymer may
have an index of refraction between the refractive indices of the base
layer and air. For example, the polymer may be a fluorinated carbon.
Similar to the embodiment of FIG. 11, the spacers in this embodiment may
have approximately the same refractive index as the anti-reflection
coating. For example, the spacers may be made of the same polymer as the
anti-reflection coating.

[0060] As previously discussed, two surfaces may have a tendency to stick
together once the surfaces come into contact. This effect has been
described herein as "wetting." When the surfaces are glossy, the wetting
effect or the tendency to stick together may be exacerbated. The energy
to separate the two surfaces may be described as:

W=2Aγ

W may be the work of cohesion, A may be the surface area of the surfaces
and γ may be the surface free energy. As the surface free energy
decreases, the work of cohesion is reduced at the surfaces and may more
easily separate. Stated differently, the likelihood of the two surfaces
sticking together decreases as the surface free energy decreases.
Accordingly, it may be desirable to treat the bottom surface of the touch
panel and the top surface of the display module with a coating to achieve
a low surface energy. The low surface energy coating may provide lower
surface energy than the original surface, in which the original surface
may be, for example, an anti-reflection surface, hard coating surface,
plastic surface, glass surface and so on.

[0061] As one example, the low surface energy treatment may be a
fluorinated polymer coating. The low surface energy treatment may be
deposited in conjunction with the spacers and may be deposited as a
direct coating on glass. Although the spacers may reduce the likelihood
of the surfaces coming into contact with one another, the low surface
energy treatment may also be used in conjunction with the spacers. In
between the spacers, local deformation from, for example, a stylus
touching a screen, may cause the surfaces to come into contact with one
another. Thus the low surface energy treatment may reduce the tendency of
the surfaces to stick together. The low surface energy treatment may be
deposited again, with the spacers, as a film laminated on glass with the
low surface energy coating on top of it. The low surface energy treatment
may be deposited on either the back surface of the touch panel and/or
cover glass, the front surface of the display module or both. Similar to
the anti-reflection coatings, the low surface energy treatment may be
applied to the surfaces using various techniques including, but not
limited to, air spray, spin coating, photolithography, embossing and so
on. Additionally, the thickness of the low surface energy treatment once
it is deposited may be less than the diameter of the spacers.

[0062] FIG. 12 is a flowchart generally describing one embodiment of a
method 1200 for reducing the appearance of optical effects on a display.
In the operation of block 1210, an enclosure may include a first surface
and a second surface. The enclosure may be a casing and may surround at
least the first surface and the second surface. The first surface and the
second surface may be glossy surfaces. In one example, the first surface
may be a cover lens that may protect the second surface and the second
surface may be a display module. In another example, the first surface
may be a touch panel on an electronic device that may include touch panel
functionality. The touch panel may also serve the purpose of protecting
the second surface. The display module may be, for example, a display
polarizer for the electronic device and may be made of various materials
including, but not limited to, glass, a TAC film, a PET film and so on.

[0063] In the operation of block 1220, a distance may be defined between
the first and second surfaces. The distance may depend upon the form
factor of the electronic device. For example, as the profile of the
electronic device becomes thinner, the distance between the first and
second surfaces may also decrease. As noted in the operation of block
1230, the distance between the first and second surface may also change.
As previously discussed, the electronic device may include touch panel
functionality. For example, a user may use a stylus to select an option
that may be displayed on the electronic device. The user may physically
touch the stylus to the touch panel and cause the touch panel to
temporarily curve in a downwardly direction toward the display module
surface. Additionally, as described in the operation of block 1240, an
air gap may be defined between the first and second surface. In
particular, the distance between the first and second surface may be the
air gap.

[0064] In the operation of block 1250, a minimum distance may be
maintained between the first and second surface by employing the use of
spacers. The spacers may physically maintain the minimum distance between
the two surfaces. For example, as the touch panel curves down toward the
display module, the touch panel may physically come into contact with the
spacers before the touch panel physically touches the display module. The
minimum distance may be approximately equal to the diameter of the
spacer. As previously discussed, the spacers may be beads that may be
spherical beads, elliptical beads, egg shaped and so on. In an exemplary
embodiment, the spacers may be any shape that may not have any edges or
corners. By using shapes without edges or corners, the likelihood of
sparkling and other optical effects is reduced.

[0065] Although the present invention has been described with respect to
particular apparatuses, configurations, components, systems and methods
of operation, it will be appreciated by those of ordinary skill in the
art upon reading this disclosure that certain changes or modifications to
the embodiments and/or their operations, as described herein, may be made
without departing from the spirit or scope of the invention. Accordingly,
the proper scope of the invention is defined by the appended claims. The
various embodiments, operations, components and configurations disclosed
herein are generally exemplary rather than limiting in scope.